1. Field of the Invention
The present invention relates to an x-ray photographing apparatus and, more particularly, to an x-ray photographing apparatus including a bed apparatus suitable for photography of circulatory organs, such as blood vessels of lower limbs, by employing various photographing methods.
2. Description of the Related Art
A conventional x-ray photographing apparatus for circulatory organs will be described below with reference to FIG. 1. This circulatory organ x-ray photographing apparatus comprises a photographing system 10 for obtaining an x-ray film image as a photographed image by using a film changer 10A, an x-ray fluoroscopic system 20 for obtaining a fluoroscopic image by using an image intensifier (to be referred to as an I.I. hereinafter) 20A to determine a photographing position, and displaying it on a monitor 20B, and a catheter bed 30 having a top plate unit 30A which can be horizontally moved. In addition to these components, the x-ray photographing apparatus includes various types of electrical units (not shown), e.g., a high-voltage generator and a control unit. In addition, a contrast medium injector (not shown) is arranged near the catheter bed 30.
An example of photography of blood vessels of the lower limbs of a subject to be examined by using the circulatory organ x-ray photographing apparatus will be described below with reference to FIG. 1. While the top plate unit 30A on which a subject 200 is placed is horizontally moved, fluoroscopic x-rays are emitted from an x-ray tube unit 20C of the fluoroscopic system 20. With this operation, a fluoroscopic image of the subject 200 is displayed on the monitor 20B. An operator (not shown) injects a catheter (not shown) into a blood vessel of the subject 200 while observing the fluoroscopic image, thus recognizing a position, in the subject 200, where the distal end of the catheter should reach. Therefore, the operator can move the distal end of the catheter to a predetermined position in the subject while observing the fluoroscopic image. The top plate unit 30A is further moved horizontally to move a portion, of the subject 200, at which the distal end of the catheter is located, to the position of the film change 10A of the photographing system 10. Subsequently, a contrast medium is injected from the contrast medium injector to the portion, of the subject 200, at which the distal end of the catheter is located, through the catheter. At substantially the same time, photographic x-rays are emitted from the x-ray tube unit 10B of the photographing system 10 to form an x-ray photographic image on an x-ray film in the film changer 10A.
The above description is associated with a normal photographing method with respect to a portion of lower limbs. Instead of this normal photographing method, a divisional photographing method is also used to photograph a portion of lower limbs. In this divisional photographing method, it is required that the top plate unit 30A be moved step by step at a relatively high speed. In the case shown in FIG. 1, the number of steps is five. More specifically, while the top plate unit 30A is horizontally moved to sequentially move the subject 200 to positions P1, P2, P3, P4, and P5, photographic x-rays are sequentially emitted from the x-ray tube unit 10B of the photographing system 10, thereby respectively forming x-ray photographic images on different x-ray films which are sequentially changed in the film change 10A. Therefore, a plurality of x-ray photographic images (x-ray film images) of different portions of the lower limbs can be obtained. This photographing operation is equivalent to an operation of photographing the entire region of the lower limbs in divisions.
Instead of using the normal photographing method or the divisional photographing method to photograph a portion of lower limbs, a method of photographing the entire region of lower limbs by one photographing operation is also available. In this photographing method, an elongated x-ray film is used.
FIG. 2 shows an arrangement of an x-ray photographing apparatus for photographing the entire region of lower limbs by using an elongated x-ray film. As shown in FIG. 2, a horizontally movable top plate unit 40A is arranged on a rectangular catheter bed 40. An elongated x-ray film 40B is stored in the catheter bed 40. The x-ray film 40B has a size enough to cover the entire region of the lower limbs of subject 200 to be examined. An x-ray tube unit 50 is fixed to a ceiling.
The entire region of the lower limbs is photographed in the following manner by using the x-ray photographing apparatus having the above-described arrangement. An x-ray radiation region and the position of the elongated x-ray film 40B are caused to coincide with each other by moving either the catheter bed 40 or the x-ray tube unit 50. The top plate unit 40A is moved to locate the lower limb region of the subject 200 immediately above the elongated x-ray film 40B. Subsequently, x-rays are emitted from the x-ray tube unit 50, thus obtaining an x-ray photographic image (x-ray film image) of the entire region of the lower limbs.
In the above-described conventional x-ray photographing apparatus, however, the following problem is posed. When the partial region shown in FIG. 1 is to be photographed in divisions, or when the entire region shown in FIG. 2 is to be collectively photographed by using an elongated film, a special catheter bed must be used in accordance with a photographing method. For this reason, in order to realize an apparatus which can arbitrarily perform a divisional photographing operation and a photographing operation using an elongated film, two catheter beds must be arranged. Therefore, a large space is required to arrange the two catheter beds, and the apparatus is complicated.